Conventionally, there has been suggested a device which assists a user in walking by applying a torque around a leg joint (a hip joint, a knee joint, or an ankle joint) to a user's body (for example, refer to Japanese Patent Laid-Open No. 2003-135543). In addition, there has been suggested a system which controls the walking assist device in such a way as to add autonomy to the walking assist rhythm of the walking assist device while following changes in the user's locomotion rhythm (for example, refer to Japanese Patent Laid-Open No. 2004-073649).